For the Café de Paris sauce: Rinse the anchovy and pat dry. Peel and chop the shallots. Puree both with butter, capers, mustard, ketchup and cognac using a hand blender. Wash tarragon, shake dry.
Pluck the leaves. Put some stems aside for garnishing, pluck off the rest of the leaves, chop them and stir them into the butter. Season butter with Worcester sauce, salt and pepper. Cover and chill for 30 minutes.
Dab meat dry and cut into 4 pieces (approx. 3 cm high). Fry in hot clarified butter for about 1 minute on each side. Season with salt and pepper. Then fry on medium heat for 3-4 minutes on each side.
Wrap steaks in aluminium foil and let them rest for about 5 minutes.
Finish the sauce: Whip the cream until stiff, set aside 1 tablespoon. Bring cream to the boil in a small pot. Gradually fold in cold seasoned butter in pieces at low heat. Fold in the rest of the whipped cream.
Arrange steaks with Café de Paris sauce. Serve with green salad and chips. Drink tip: strong red wine, for example a Bordeaux.